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Departments of
*Anesthesia and Critical Care and
Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
Address correspondence and reprint requests to Kyung W. Park, MD, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215. Address e-mail to kpark{at}caregroup.harvard.edu
Analogous to vascular endothelium, bronchial epithelium modulates bronchomotor activity by releasing epithelium-derived relaxing factors. Cardiopulmonary bypass (CPB) is associated with endothelial dysfunction. We examined whether CPB may be associated with bronchiolar epithelial dysfunction in pigs. Pigs were exposed to normothermic CPB for 1.5 h and then separated from CPB. Lung tissues were biopsied before and 30 min after CPB. For time control, lung tissues were biopsied at baseline and after 2 hr of anesthesia. Bronchioles measuring about 100 µm were dissected, and the epithelium was either left intact or denuded. Each bronchiolar segment was preconstricted with 10 µM 5-hydroxytryptamine and relaxation responses to nitroprusside 10-910-4 M, isoproterenol 10-910-4 M, or the inhaled anesthetics halothane or isoflurane 02.5 minimum alveolar anesthetic concentration were examined in vitro by videomicroscopy. Bronchiolar segments demonstrated concentration-dependent relaxation responses to each of the dilators examined. Epithelial denudation reduced bronchodilation to isoproterenol, isoflurane, and halothane, but not to nitroprusside. Bronchodilation was not significantly affected by CPB. We conclude that, unlike vascular endothelial function, porcine bronchiolar epithelium-modulated bronchomotor activity is not significantly affected by normothermic CPB.
Implications: Normothermic cardiopulmonary bypass does not result in epithelial dysfunction in pigs. Epithelium-dependent and epithelium-independent bronchodilators may be equally effective before and after cardiopulmonary bypass.
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